LINQ Lambda query 'select' not working with oData

Question

I'm currently trying to understand some of the fundamentals with LINQ. I have been using LINQPad to query the Netflix OData source.

Source: http://odata.netflix.com/v2/Catalog/

I can't seem to select single properties when using a lambda query - the comprehension query works perfectly. I found a snippet of code that performs a more complex query using lambdas on the Netflix oData source, and this seems to work fine for returning one property of the entity.

// works fine
var compQuery = from t in Titles
                where t.ReleaseYear == 2007
                select new { t.Name };
compQuery.Dump();   



// fails: "Can only specify query options (orderby, where, take, skip) after last navigation."
var lambdaQuery = Titles
            .Where(t => t.ReleaseYear == 2007)
            .Select(t => t.Name);

lambdaQuery.Dump(); 


// works fine - found on SO.
var lambdaQuery2 = People
    .Expand("TitlesActedIn")
    .Where(p => p.Name == "George Lucas")
    .First()
    .TitlesActedIn.Select(t => t.ShortName);              

lambdaQuery2.Dump(); 

Could anyone shed some light as to why the basic lambda query is failing when asked to return one property?

Answer 1

OData doesn't have support for projecting to properties - you can work around this though:

var lambdaQuery = Titles
            .Where(t => t.ReleaseYear == 2007)
            .Select(x=> new { x.Name })
            .AsEnumerable()
            .Select(t => t.Name);

Using AsEnumerable() forces the last part of the query to be executed in Linq-to-Objects context (instead of an OData query) where the projection works just fine.

Answer 2

Try this- it is what is actually equivalent to your first one:

// fails: "Can only specify query options (orderby, where, take, skip) after last navigation."
var lambdaQuery = Titles
            .Where(t => t.ReleaseYear == 2007)
            .Select(t => new { t.Name });

lambdaQuery.Dump(); 

Answer 3

Using the answers given, I have ran some tests and found some interesting things regarding execution time:

// Avg Execution Time: 5 seconds
var query1 = Titles
            .Where(t => t.ReleaseYear == 2007)
            .Select(t => new {t.Name});     
query1.Dump();


// Avg Execution Time: 15 seconds
var query2 = Titles
            .Where(t => t.ReleaseYear == 2007)
            .AsEnumerable()
            .Select(t => t.Name);       
query2.Dump();

So am I right in thinking that in query 1, only the 'Name' property is being returned? Whereas in query 2, the 'AsEnumerable()' method is bringing back the entity with all property values, hence longer execution time?